Most recent entries from all

EUVD-2026-26222

fkie_cve-2021-29136

Open Container Initiative umoci before 0.4.7 allows attackers to overwrite arbitrary host paths via a crafted image that causes symlink traversal when "umoci unpack" or "umoci raw unpack" is used.

GHSA-9m95-8hx6-7p9v — Improper input validation in umoci

Affected: Go: github.com/opencontainers/umoci

### Impact

umoci 0.4.6 and earlier can be tricked into modifying host files by creating a malicious layer that has a symlink with the name "." (or "/"). Because umoci deletes inodes if they change types, this results in the rootfs directory being replaced with an attacker-controlled symlink. Subsequent image layers will then be applied on top of the target of the symlink (which could be any directory on the host filesystem the user running umoci has access to).

While umoci does have defences against symlink-based attacks, they are all implemented by resolving things relative to the rootfs directory -- if the rootfs itself is a symlink, umoci resolves it first.

This vulnerability affects both "umoci unpack" and "umoci raw unpack".

### Patches This issue has been patched in umoci 0.4.7, see the references section for the specific commit which fixed this vulnerability.

### Workarounds Note that if you use umoci as an unprivileged user (using the --rootless flag) then umoci will not be able to overwrite any files that your user doesn't have access to. Other possible mitigations are to run umoci under an LSM profile such as AppArmor or SELinux to restrict the level of access it has outside of container image directories.

### References * [oss-security public disclosure](https://www.openwall.com/lists/oss-security/2021/04/06/2) * [patch](https://github.com/opencontainers/umoci/commit/d9efc31daf2206f7d3fdb839863cf7a576a2eb57)

### Credits Thanks to Robin Peraglie from Cure53…

gsd-2021-29136

OESA-2021-1151 — umoci security update

Affected: openEuler:20.03-LTS-SP1: umoci

Umoci modifies Open Container images. Umoci intends to be a complete manipulation tool for OCI images. In particular, it should be seen as a more end-user-focused version of the oci-image-tools provided by the OCI. Security Fix(es): Open Container Initiative umoci before 0.4.7 allows attackers to overwrite arbitrary host paths via a crafted image that causes symlink traversal when "umoci unpack" or "umoci raw unpack" is used.(CVE-2021-29136)

openSUSE-SU-2021:0548-1 — Security update for umoci

Security update for umoci

SUSE-SU-2021:1116-1 — Security update for umoci

Security update for umoci

UBUNTU-CVE-2021-29136

Affected: Ubuntu:20.04:LTS: umoci, Ubuntu:22.04:LTS: umoci

Open Container Initiative umoci before 0.4.7 allows attackers to overwrite arbitrary host paths via a crafted image that causes symlink traversal when "umoci unpack" or "umoci raw unpack" is used.